Calenders for pressing laundry



March 2, 1965 H. c. A. ZWAARD CALENDERS FOR PRESSING LAUNDRY Filed Jan.17, 1963 INVENI OR 6'. A. ZWAARD BY KM HENDRICUS ATTORNEY:

United States Patent 3,171,221 CALENDERS FOR PRESSING LAUNDRY HendricusC. A. Zwkaard, Prineesselaan 12, Rijswijk, South Holland, NetherlandsFiled Jan. 17, 1963, Ser. No. 252,197 Claims priority, applicationNetherlands, Jan. 23, 1962, 273,838 3 Claims. (Cl. 38-55) The inventionrelates to a calender for pressing laundry with one or more rollersrotatably arranged in heated troughs, said rollers being supported inarms attached to the frame of the calender and adapted to execute aswinging movement, means being provided for swinging said arms to liftthe rollers out of the troughs. During the working of the calender therollers are to be held in the troughs with a certain pressure in orderto obtain the required treatment of the laundry. In the case that nolaundry is treated in the calender the rollers are to be lifted out ofthe troughs because otherwise the lining of the rollers would bescorched. Hitherto the lifting of the rollers was obtained in amechanical way whereas also hydraulically operated means were used.These embodiments have the disadvantage that in a mechanical operatingdevice the pressure of the rollers in the troughs cannot be controlledeasily and in applying hydraulically operated means double-actingcylinders are used so that both the pressing and lifting is obtainedhydraulically, and if there is some trouble in the hydraulicinstallation the rollers cannot be lifted out of the troughs and if theyare already in their lifted position they fall back in the troughs. Onehas the same disadvantage when instead of a liquid an other fluid, forexample air, is used.

The invention has for its object to provide a very simple lifting devicein which it is easy to control the pressure of the rollers in thetroughs and in which the above mentioned disadvantage has beeneliminated. According to the invention said means for swinging said armsconsist of at least one hinged cylinder and of at least one hingedpretensioned spring, both mounted between one of said arms and a fixedpart of the calender, such that the cylinder is working in the directionfor pressing the rollers in the troughs and the spring is biasing thearm in opposite direction. The advantage is here that a very simplecylinder can be used and that when the supply of electricity or ofpressure air is interrupted the rollers are automatically lifted out ofthe troughs by said spring,

In a very effective embodiment of the calender according to theinvention the center lines of said spring encloses such an angle withthe corresponding arm that the distance between the hinge of said armand the center line of said spring increases when said arm swings in thedirection of the easing of said spring, such that the moment exerted bythe force of said spring in relation to said hinge has a substantiallyconstant value.

In such a device the said spring in the uppermost position of the rollerhas toexert such a force that the weight of the roller can be supported.

The tension in the spring will increase during the lowering of theroller and will be in fact inversely proportional to the length of saidspring.

In the case that the spring would be arranged in such a way that saidspring was directed perpendicularly to the arm being in its lowermostposition, at a certain fixed value of the lifting height the increase inthe spring pressure at the lowering of the roller would be so large thata cylinder with an extremely large diameter would be required to producethe necessary force with a certain pressure of the fluid.

It is possible to prevent the application of such a large cylinder byreducing the increase of the spring tension ice by means of an extremelylong pressure. spring. Such a long pressure spring however is: verydiflicult to accommodate. Owing to the described oblique position ofsaid spring it is possible to have. such an arrangement that the momentexerted by the force of said spring has a substantially constant valueso that the desired a ge lifting height in order to have a goodaccessability of the trough can be obtained, whereas a spring of normallength and a. cylinder with a small diameter can be used.

According to the invention the distance between the point of connectionof said cylinder to said arm and the hinge of said arm can be adjusted.So it is possible. when applying a series of rollers to press, ifrequired, one of the rollers with a greater pressure in the trough.

The invention will 'be elucidated in the following description of anembodiment of a calender in accordance with the invention.

In the single figure of the drawing is shown a diagrammatic elevation ofa calender according to the invention with a number of rollers rotatablyarranged in corresponding troughs, parts being shown in section. Onlyone trough with the corresponding roller is completely drawn and theinvention will be descrribed in connection with this part of thecalender. In a trough 2 mounted on a frame 1 a roller 3 is adapted torotate. The roller 3 is supported in bearings 4 which are mounted inarms 5. The arms 5 are hinged on a shaft 6 mounted in the frame 1. Apneumatic cylinder 7 is hinged to the frame 1 at 8 whereas the free endof the piston rod 9 of the cylinder is hinged to the free end of the arm5 at opening 10. The cylinder hinge point to the arm 5 may be adjustedby pivot ing the piston rod 9 in any one of the series of openings 10,10a, 10b. In telescopically cooperating sleeves 11 and 12 a spring 13 ismounted, sleeve 11 being hinged to the frame 1 at 14, the sleeve 12 atthe other end of the spring being hinged to the arm 5 at 15. If pressureair is supplied to the cylinder 7 through upper duct 16 the roller 3 ispressed in the trough 2 against the action of spring 13.

The sleeves 11 and 12 with the spring 13 are positioned obliquely inrelation to the arm 5 so that the distance between the center of theshaft 6 and the center line 14-15 of the spring 13 increases when thearm 5 moves in the position 5a. The increase of the distance p to thedistance pa is defined in such a way that the product of the forceexercised by the spring 13 and the arm p of the couple remainssubstantially constant. So it is possible to allow with a rather smallspring a rather large spring travel, so that in the position 3a theroller 3 is lifted sufficiently far out of the trough without thenecessity that the pneumatic cylinder 7 has to exercise a too largeforce when pressing downwardly the roller 3.

What I claim is:

1. In a calender the combination of a frame, a fixed member on saidframe, at least one arm pivoted to said frame about a hinge axis, aroller journaled in said arm for rolling against said fixed member,fluid pressure jack means pivotally connected to each of and betweensaid arm and said frame, said fluid pressure jack means being soarranged that application of fluid pressure will move the :arm androller toward said fixed member, a spring mounted in compression, meanspivotally connecting one end of said spring to said arm and the otherend to said frame, said spring urging the arm to lift the roller fromsaid fixed member, and said spring having a center line disposed at suchan angle with the arm that the distance between said hinge axis of thearm and the center line of said spring increases when said arm swings inthe direction of the easing of said spring to maintain a substantiallyconstant moment of force exerted by the spring as the arm moves saidroller upwardly away from the fixed member.

2. In a calender the combination of a frame, a fixed member on saidframe, at least one arm pivoted to said frame about a hinge axis, arotatable roller journaled in said arm for rolling against said fixedmember, a fluid pressure cylinder pivoted to said frame and including apiston and piston rod, said piston rod being pivotally connected to saidarm, said fluid pressure cylinder being so arranged that application offluid pressure to the cylinder will move the arm and roller toward saidfixed member, a spring mounted between a pair of telescoping elementsone pivoted to said arm and the other to said frame, said spring urgingthe arm to lift the roller from said fixed member, and said springhaving a center line disposed at such an angle with the arm that thedistance between said hinge axis of the arm and the center line of saidspring increases when said arm swings in the direction of the easing ofsaid spring, to maintain a substantially constant 4, moment of forceexerted by the spring as the arm moves said roller upwardly away fromthe fixed member.

3. In a calender the combination according to claim 2 wherein means isprovided for pivotally connecting said piston rod to said arm atdifferent distances from said hinge axis.

References Cited by the Examiner UNITED STATES PATENTS 1,637,282 7/27Schlatter 3852 1,936,027 11/33 Pointon 3857 X 2,138,397 11/38 Cannity3852X 2,729,003 1/56 Cohu et al 3852 JORDAN FRANKLIN, Primary Examiner.

DAVID J. WILLIAMOWSKY, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,171,221 March 2, 1965 Hendricus C. A. Zwaard It is hereby certifiedthat error appears in the above numbered patent requiring correction andthat the said Letters Patent should read as corrected below.

In the grant, lines 1 and 12, and in the heading to the printedspecification, line 3, name of inventor, for "Hendricus C. A. Zwkaard",each occurrence, read Hendricus C. A. Zwaard Signed and sealed this 27thday of July 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Altesting Officer Commissioner ofPatents

1. IN A CALENDER THE COMBINATION OF A FRAME, A FIXED MEMBER ON SAIDFRAME, AT LEAST ONE ARM PIVOTED TO SAID FRAME ABOUT A HINGE AXIS, AROLLER JOURNALED IN SAID ARM FOR ROLLING AGAINST SAID FIXED MEMBER,FLUID PRESSURE JACK MEANS PIVOTALLY CONNECTED TO EACH OF AND BETWEENSAID ARM AND SAID FRAME, SAID FLUID PRESSURE JACK MEANS BEING SOARRANGED THAT APPLICATION OF FLUID PRESSURE WILL MOVE THE ARM AND ROLLERTOWARD SAID FIXED MEMBER, A SPRING MOUNTED IN COMPRESSION, MEANSPIVOTALLY CONNECTING ONE END OF SAID SPRING TO SAID ARM AND THE OTHEREND TO SAID FRAME, SAID SPRING URGING THE ARM TO LIFT THE ROLLER FROMSAID FIXED MEMBER, AND SAID SPRING HAVING A CENTER LINE DISPOSED AT SUCHAN ANGLE WITH THE ARM THAT THE DISTANCE BETWEEN SAID HINGE AXIS OF THEARM AND THE CENTER LINE OF SAID SPRING INCREASES WHEN SAID ARM SWINGS INTHE DIRECTION OF THE EASING OF SAID SPRING TO MAINTAIN A SUBSTANTIALLYCONSTANT MOMENT OF FORCE EXERTED BY THE SPRING AS THE ARM MOVES SAIDROLLER UPWARDLY AWAY FROM THE FIXED MEMBER.